The present invention relates to a ball bearing cage, a ball bearing, and to a method of producing, or forming a ball bearing cage.
Ball bearing cages for arranging the individual balls of a ball bearing are well known in the art, and they serve for holding the balls in position at equal distances in circumferential direction of the ball bearing. With ball bearing cages of this type, a so-called ball pocket clearance is of high importance with respect to wear behaviour of the ball bearing cage. The ball pocket clearance is defined as the mobility of the ball in the ball pocket in axial and radial directions.
Due to misalignment of the bearings in a housing, or in case of tilt of bearing surfaces, balls within a set of balls may move with different speeds. As a result, leading or trailing balls tend to move away from the ball pocket position, thus applying forces on the ball bearing cage in circumferential direction. This may result in excessive wear.
DE 10 2010 047 962 A1 proposes a ball bearing cage wherein the ball pockets are in the form of elongated holes. Herein, the longest dimension of the ball pocket is provided in circumferential direction of the ball bearing cage and exceeds the diameter of the balls by about 20% to about 55%.
Because the ball bearings are formed as elongated holes in circumferential direction, a smaller number of balls can be received, such that static and dynamic load rating of the ball bearing is reduced. Since, in addition, the force applied to the contact surface of ball and cage for driving the cage is not applied in circumferential direction of the cage, the force contains a force component in radial direction of the cage which undesirably displaces the cage from the center thereof. As a result, wear of the ball bearing cage can proceed rapidly.